In not advance published German patent application 197 14 674, a measuring device of the above-mentioned type is described, in which a test card including several test strips can be inserted. The test card is located in a sleeve, from which it can be pulled out so far that a test strip becomes exposed, so that the liquid to be investigated can be applied to the test field. For this purpose, the device has to be opened, to allow the operating person to grasp the test card and pull it from the sleeve.